Continuous strip feeding self-alignment apparatus

ABSTRACT

A feed roll stand for feeding and cutting to length measured metal strip comprises a pair of pinch rolls mounted on a moveable platform supported on horizontal rollers. The platform is connected to a roll stand base by a compression spring centering device. The pinch rolls are thus moveable from their normal centered position with respect to the roll stand support base for distances limited by the centering device compression spring. A pair of guide rollers are mounted on vertical shafts extending downwardly from the underside of the platform. The guide rollers engage horizontal guide tracks which are mounted to the roll stand support base so that the path the guide rollers travel along the tracks is offset at an angle (approximately in the order of 5*) from the normal axis of rotation of the pinch rolls. The axis of these tracks, if extended, would intersect on the exit side of the pinch rolls. In operation, slight parallel misalignment of the pinch rolls tends to urge the strip laterally from the normal center path of travel; however edge guides constrain transverse movement of the strip and, instead, the moveable platform permits the roll stand to arcuately shift in the opposite direction. Because the movement is arcuate, and the pinch rolls generally drive the strip in a direction normal to their axes of rotation, the pressure of the strip against the edge guides is relieved.

United States Patent [191 Buta [ 1 Nov. 19, 1974 CONTINUOUS STRIP FEEDING SELF-ALIGNMENT APPARATUS [75] Inventor: John R. Buta, Salem, Ohio [73] Assignee: Paxon Machine Company, Salem,

Ohio

[22] Filed: July 23, 1973 [21] Appl. No.: 381,909

Primary ExaminerRichard A. Schacher 1 1 ABSTRACT A feed roll stand for feeding and cutting to length measured metal strip comprises a pair of pinch rolls mounted on a moveable platform supported on horizontal rollers. The platform is connected to a roll stand base by a compression spring centering device. The pinch rolls are thus moveable from their normal centered position with respect to the roll stand support base for distances limited by the centering device compression spring. A pair of guide rollers are mounted on vertical shafts extending downwardly from the underside of the platform. The guide rollers engage horizontal guide tracks which are mounted to the roll stand support base so that the path the guide rollers travel along the tracks is offset at an angle (approximately in the order of 5) from the normal axis of rotation of the pinch rolls. The axis of these tracks, if extended, would intersect on the exit side of the pinch rolls. In operation, slight parallel misalignment of the pinch rolls tends to urge the strip laterally from the normal center path of travel; however edge guides constrain transverse movement of the strip and, instead, the moveable platform permits the roll stand to arcuately shift in the opposite direction. Because the movement is arcuate, and the pinch rolls generally drive the strip in a direction normal to their axes of rotation, the pressure of the strip against the edge guides is relieved.

16 Claims, 5 Drawing Figures PATENTELHUVISIBM 3-,848'788 SHEET 3 0F 4 .FIG.4.

CONTINUOUS STRIP FEEDING SELF-ALIGNMENT APPARATUS The present invention relates to a continuous strip metal feeding and cutting to length pinch roll stand, and more particularly to a pinch roll stand which is selfadjusting to maintain the strip metal centered between the rolls.

Metal strip pinch roll stands generally comprise at least one pair of opposed pinch rolls which are driven to feed continuous metal strip from a coil into a cutting, forming or other operation for further fabrication or treatment of the metal strip. Usually, the pinch rolls are controlled to feed a pre-selected amount of strip into the subsequent operation. For many operations, such as cutting of the strip into short lengths, it is essential that the strip be fed in accurately controlled amounts and along a true longitudinal path to insure the production of substantially perfectly rectangular pieces. Offcenter travel of the strip may result in edge damage and irregular pieces being formed in the cutting operation.

The problems of misalignment of pinch rolls and consequent longitudinal misalignment of traveling continuous metal strip have long been recognized, and a number of prior art devices are known, the purpose of which is to insure such true and accurate travel of the metal strip. Among these are electronic control devices, synchronous geared pinch rolls with suitable control devices, and slide-bar mounted double pinch rolls. All of these prior art devices are complicated and relatively expensive.

It is an object of the present invention to provide a self-aligning, self-adjusting metal strip pinch roll stand of simple, efficient and novel design which avoids the necessity for electronic controls, slide-bar mounted double rolls, or other prior art devices for maintaining correct alignment of metal strip fed therethrough.

In accordance with the present invention there is provided a strip feed pinch roll stand containing a pair of opposed pinch rolls mounted on a transversely shiftable platform engaged in fixed guide track means. The guide track means constrain the platform, and its associated pinch rolls, to traverse or shift arcuately in response to a tendency of misaligned rolls to urge the strip laterally against the edge guides on one side of the strip, as would be the caSe with an immovable roll stand. However, with the present invention, instead of damaging the edge of the strip against its edge guides, the arcuate traverse of the roll stand in a direction opposite to the direction of thrust against the strip relieves the pressure between the strip and the strip edge guides and tends to realign the rolls and strip in that roll stand. It will be understood that movement of the roll stand to either the right or the left is quite discreet, and such hunting is substantially continuous to maintain the strip in alignment, on an average, at all times.

In accordance with one aspect of the invention, the moveable platform is engaged with fixed guide tracks which are offset at a slight angle from the normal transverse axes of rotation of the pinch rolls, wherein an extension of the axes of said tracks intersect on the exit side of the roll stand.

In accordance with another aspect of the invention, the fixed guide tracks are adjustable within a range of off-set angles so that a desired off-set angle may be selected and the guide tracks set at that angle. Generally, an off-set angle greater than zero but not greater than ten degrees is an adequate operable range of adjustment.

The off-set angle as that term is used in this specification and in the claims means the horizontal plane angle formed between the normal axes of rotation of the pinch rolls and the longitudinal axis of a guide track. The longitudinal axis of a guide track is the path of travel of guide rolls or equivalent means (described in detail hereinbelow) along the guide track.

Preferably, a pair of guide tracks are employed, and the offset angle of each of the guide tracks is equal and opposite so that imaginary lines drawn along the longitudinal axes of each of the guide tracks intersect at a point on the longitudinal center axis of true stn'p travel when the strip travel is on-center along a line perpendicular to the normal axes of rotation of the pinch rolls.

In accordance with a preferred embodiment of the invention, the opposed pinch rolls are mounted in journal stanchions which are secured to a platform supported by horizontal rollers, wherein the platform is capable of limited substantially transverse movement. A pair of guide rollers are mounted on vertical shafts extending downwardly from the underside of the platform to engage a corresponding pair of fixed guide tracks. The guide tracks are adjustably mounted, relative to the normal axes of rotation of the pinch rolls, to a roll stand base.

The centering device may consist of any biasing means, such as one or more springs, secured between the moveable platform and the roll stand base orany other fixed structure. As employed, in the specification and claims, the term fixed used with reference to a member or structure, unless the context clearly requires otherwise, means that the member or structure does not move with the moveable platform and its associated pinch rolls.

Because of the mobility of the roller-supported, moveable platform on which the pinch rolls are mounted, roll misalignment tends to move the pinch rolls and their associate moveable platform transversely of the line of true strip travel. However, the offset, or skewed positions of the fixed guide tracks relative to the normal axis of rotation of the pinch rolls imparts a rotational vector to this movement which is equal and opposite to the lateral thrust against the traveling metal strip. In this manner, the arcuate movement of the pinch rolls functions to maintain the rolls in a position relative to the instantaneous center of rotation of the off-center travel of the strip, wherein the tendency towards off-center strip travel is automatically and substantially instantaneously corrected. The term instantaneous center of rotation has its usual, accepted meaning, i.e., any plane body having plane motion which is neither entirely rectilinear nor entirely rotative, but a combination of the two, at any instant has rotary motion about a (moving) point. This point is the instantaneous center of rotation. When a travelling metal strip deviates off-center, a rotative component is added to the rectilinear component of true strip travel.

An understanding of the invention may now be further facilitated by reference to the following description of a preferred embodiment thereof which illustrates, but is not intended to limit, the invention. In connection with the detailed description, reference should be had to the drawings which form a part thereof and wherein:

FIG. 1 is a schematic view in elevation showing a strip feeding roll stand feeding metal strip from a coil into a strip shearing die set;

FIG. 2 is a front elevational view of a strip roll feed stand in accordance with the invention;

FIG. 3 is a partially broken away plan view of the roll feed stand of FIG. 2;

FIG. 4 is a partially broken away side view in elevation of the roll feed stand of FIG. 2 and FIG. 5 is a plan view of the roll feed stand similar to FIG. 3, but with adjustments made of the parts shown ready for operation.

Referring to FIG. 1, a coil of metal strip S is shown supported on a coil stand 2. The strip passes between sets of edge guides 3, between pinch rolls l6 and 18, and then on to a forming station, such as a shear 5. A strip pinch roll stand is shown generally at 4, essentially comprising a lower pinch roll 16 and an upper pinch roll 18 contained within a pair of pinch roll stanchions 26. Strip pinch roll stand 4 is supported on a base 10. A strip cutting shear 5 has an upper die 6 and a lower die 7, and is supported on a base 8. A suitable drive means (not shown in this view but described hereinafter with respect to FIG. 2) rotate pinch rolls l6 and 18 to draw metal strip from the coil stand 2 and feed it in the direction shown by the arrow A. The strip shear 5 cuts the metal strip into short, rectangular sections 9. The schematic arrangement of FIG. 1 is typical of the use to which a strip feeding machine may be put, and the need for accurate and true travel in advancing metal strip into shear 5 (or other fabricating devices) is apparent.

Referring now to FIG. 2, a strip pinch roll stand in accordance with the invention is mounted on the support base 10 which has a support platform 12 and a pair of cross pads 14 affixed thereto. Referring jointly to FIGS. 2 and 4, a lower pinch roll 16 and upper pinch roll 18 are journaled at opposite ends in stationary journal bearings 20 and adjustable journal bearings 22. Journal bearings 20 and 22 are mounted in journal chocks 24 affixed between upright stanchions '26 of pinch roll stand 4. Stanchions 26 are connected by a lintel member 30, the two upright stanchions 26 and lintel member 30 together comprising pinch roll stand 4. At their right hand end (as viewed in FIG. 2) pinch rolls 16 and 18 are driven by spindle shafts 32 and 34, powered through reduction gear box 36, and connected by motor drive shaft 38 to drive motor 40.

Pneumatic cylinders 42 are mounted on top of each stanchion 26 to operate drive rods 44 (FIG. 4) which position adjustable journal bearings 22, and thereby upper pinch roll 18, at a predetermined distance above lower pinch roll 16. The foregoing described structure is conventional and well known in the art. Fittings, compressed air lines to the pneumatic cylinders and other accessories, and devices useful and well known to those skilled in the art are omitted from the drawings and description for the sake of simplicity and clarity.

As best seen with respect to FIG. 4, a roller mounting arrangement for pinch roll stand 4 is provided by pairs of opposed upright roller piers 46 placed front and rear of the roll stand 4. Each pier contains a pair of support and guide rollers 48, 50 mounted thereon. The left hand (as viewed in FIG. 4) roller pier 46 is partially broken away to show shafts 52 on which support rollers 48, 50 are mounted. The shafts 52 are journaled through piers 46 and fixed thereto by lock washer 54 and nuts 56. Roller piers 46 have grooves 58 formed therein between support rollers 48 and 50, extending horizontally along the entire length of each roller pier 46. The grooves 58 and the spaces 51 between support rollers 50 and moveable platform 76 provide sufficient freeboard space between, respectively, platform 76 and rollers 50, and platform cross pads 82 and roller piers 46, to permit arcuate movement of platform 76 and pads 82 relative to roller piers 46. With the structure shown, an off-set angle up to about 10 can conveniently be accommodated. Obviously, structure to accommodate off-set angles greater than 10-could be provided without departing from the spirit and interest of the invention.

Roller piers 46 are mounted on fixed tumplates 60, in opposed, facing relationship to each other. Also mounted on the tumplates 60 are guide tracks 62 which, as best shown in FIGS. 4 and 5 are essentially U-shaped in cross-section, to define grooves 64 therein. Stub shafts 66 (FIG. 4) protrude from the undersides of guide tracks 62 through turnplates 60 and are journaled in circular openings 63 formed in support platform 12 and cross pads 14. Guide tracks 62, stub shafts 66, and tumplates 60 are all rigidly affixed one to the other, as by welding. Roller piers 46 are similarly rigidly affixed to tumplates 60 as by welding. Naturally, any other suitable form of rigidly inter-connecting these members into a single unit may be employed. While grooves 64 in guide tracks 62 are preferably substantially straight, they may also be made curved.

Tumplates 60 have formed at opposite ends arcuate slots 68 (FIG. 3) within which are received bolts 70 which are rigidly affixed to and project upwardly from cross pads 14 (FIG. 4). Washers 72 and nuts 74 cooperate to hold tumplates 60 in selected adjustable positions as described in detail hereinbelow. By loosening nuts 74 tumplates 60 may be rotated about stub shaft 66 to any desired angular positionwithin the scope of movement permitted by slots 68, and, once positioned, the nuts 74 are tightened to hold tumplates 60 in place.

As best seen in FIG. 2, a moveable platform 76 has a cantilevered section 76A on which are mounted gear box 36 and motor 40. Webs 78, 80 provide structural rigidity and support to connect moveable platform 76 to cantilevered section 76A, and to a stanchion 26 of feed roll stand 28. Motor 40 and gear box 36 are conveniently mounted on cantilevered section 76A of moveable platform 76 in order to eliminate relative lateral movement between pinch rolls 16, 18 and gear box 36 due to the lateral movement of the pinch rolls, as described hereinbelow.

Centering means generally indicated at 89 comprise compression springs 92 interconnected with lugs 90, 98 and 100. Centering means 89 tends to center platform 76 and pinch rolls 16, 18 in their normal, at rest position. Lug 90 projects from platform 76 and is connected to an opposed pair of the compression springs 92 by means of shafts 96 which project from lug 90. A complementary pair of lugs 98, project upwardly from support platform 12 and compression springs 92 are respectively connected thereto by shafts 97. (A portion of spring 94 is broken away to show shaft 97. Only the outer stub end of right shaft 97 is shown). As viewed in FIGS. 2, 3 or 5, movement of moveable platform 76 leftwardly tends to compress compression spring 94 between lugs 90 and 98. Rightward movement of moveable platform 76 tends to compress spring 92 between lugs 90 and 100. Centering means 89 thus tends to return platform 76 to its normal at rest position. While a compression spring device as shown is preferred for its simplicity, obviously, any suitable centering device may be employed, such as hydraulic or electrical means.

Platform extensions 82 (as best seen in FIG. 4) project beyond the edges of moveable platform 76 and are received between support rollers 48,50. Thus, pinch roll stanchions 26, containing pinch rolls l6 and 18, and platforms 76 and 76A, together with motor 40 and reduction gear 36, constitute a unit free to move relative to fixed support base 10 and roller piers 46, as described in detail hereinbelow.

A pair of guide rolls 84 are mounted on vertically disposed shafts 86 and are affixed, one to each of platform extensions 82, by nuts 88.

In FIGS. 3 and 4, horizontal guide tracks 62 are shown positioned so that the longitudinal axes of the guide tracks 62, i.e., the path of travel of guide rolls 84 therein, are parallel to and substantially coincident with the normal axes of rotation of pinch rolls l6, 18. However, in actual operation, guide tracks 62 would be off-set skew as shown in FIG. 5. The left hand portion of FIG. 5 is broken away to show operational angulation of guide track 62; the location of guide roll 84 therein is shown in phantom. Arrows A in FIGS. 3 and 5 show the direction of strip travel through the roll stand.

The left hand turnplate 60 as viewed in FIG. 5 has been rotated in a clockwise direction about five degrees out of alignment from the normal axis of rotation of pinch rolls 16, 18. correspondingly, the right hand turnplate 60 has been rotated a similar amount, i.e., about 5, but in a counter-clockwise direction. By extending an imaginary line along the respective longitudinal axes of the left hand and right hand guide tracks 62, the lines will be seen to intersect along the center line of the direction of true feed of metal strip passing through the machine.

In operation, the guide tracks are normally offset at a selected angle of offset. Generally, any angle from zero up to ten degrees from the pinch roll normal axis of rotation is within the normal range of adjustment. A larger angle of offset is workable, but is not necessary for this particular application.

As the metal strip is fed through and between pinch rolls l6 and 18, some slight misalignment between the upper and lower pinch rolls will tend to move the pinch rolls either to the left or to the right of the line of true feed travel, depending on the roll misalignment, condition of the strip, or possibly a combination of both factors. (In the drawings, the pinch rolls are shown in their normal position, i.e., parallel and at a right angle to the longitudinal axis of true strip travel through the machine). Since the pinch rolls are mounted on a roller supported platform, any such movement will tend to move the pinch rolls either leftwardly or rightwardly, as viewed in FIG. 5. Because of the engagement of guide bearings 84 with guide tracks 64, leftward or rightward shifting of the pinch rolls and their associated frame housing is also slightly arcuate in a clockwise direction for leftward shifting, and in a counter-clockwise direction for rightward shifting. When the lateral thrust forces reacting between the rolls and the strip have been dissipated, the pinch rolls return to their normal position either by action of the spring centering means 87, by corrective movement of the rolls or both.

While the invention has been described in detail with respect to a particular preferred embodiment thereof, it will be apparent to those skilled in the art, after reading and understanding the foregoing, that many modifications and changes to the specific embodiment described may be made, which modifications and changes are nonetheless within the spirit and scope of the present invention. For instance, it is also contemplated that the respective guide tracks be set at different angles relative to the normal axes of rotation of the pinch rolls. Thus, one guide track may be set at a positive angle and the other guide track may be set at zero angle or even at a negative angle. Furthermore, it is also within the scope of the contemplated invention to solve still other strip feeding problems. By way of example, even when the pinch rolls are in reasonably good parallel alignment, the strip may still tend to drift to one side of the true longitudinal path of travel. This may be due to camber in the strip or some other strip imperfection such as top and bottom surfaces of the strip being nonparallel, or varying in thickness. Setting the guide tracks as previously described with their extended longitudinal axes intersecting on the exit side of the roll stand (positive angulation) may tend to aggravate these problems rather than to resolve them. However, by setting the guide tracks so that their extended longitudinal axes intersect on the entry side of the pinch roll stand (negative angulation), the rolls will shift transversely with the strip, rather than away from the direction of shift as previously described in the preferred embodiment of the invention. The result is that with negative angulation of the guide tracks the pinch rolls tend to drive the strip back to center. It further follows that with negative angulation of the guide tracks the importance of, and need for, strip edge guides is diminished or eliminated. Elimination of edge guides could be advantageous when running gages of strip so thin that any lateral thrust of the strip against the edge guides might damage the edges of the strip. It is intended to include all such modifications within the scope of the appended claims.

What is claimed is:

1. Apparatus for feeding metal strip comprising a support base, a pair of vertically opposed horizontally aligned pinch rolls mounted on a horizontal platform above said support base and shiftable with respect to said support base, fixed guide means on said base with which said shiftable platform is engaged, said guide means being adapted to permit horizontal arcuate transverse movement of said platform in reaction to forces of lateral thrust between said rolls and said strip.

2. The apparatus of claim 1 wherein said fixed guide means are a pair of tracks beneath opposite ends of said platform and offset so that straight line extensions of the longitudinal axes of the tracks intersect on the exit side of the said feed rolls.

3. The apparatus of claim 2 wherein said tracks are adjustable within a range of off-set angles.

4. The apparatus of claim 3 wherein said range of offset angles is between 0 and 10.

5. The apparatus of claim 1 wherein said moveable platform is mounted on anti-friction means and connected to a centering device.

6. The apparatus of claim 5 wherein said centering device includes biasing means connecting said platform to a fixed support.

7. The apparatus of claim 1 wherein said guide means comprises a pair of members having grooves formed therein, and said moveable platform has guide bearings mounted to be received within said grooves.

8. The apparatus of claim 1 wherein said shiftable platform is mounted on rollers carried on roller piers which are fixed relative to said moveable platform.

9. The apparatus of claim 8 wherein said roller piers and said guide means are mounted on tumplates which are adjustable relative to the normal position of said feed rolls.

10. Apparatus for feeding a continuous strip of metal by drawing the strip between a pair of pinch rolls comprising a support base; a pair of tumplates, one tumplate mounted at each end of said support base; a pair of guide tracks, one guide track mounted on each of said tumplates; a pair of pinch rolls mounted in a pinch roll stand, said pinch roll stand being mounted upon a moveable platform; said moveable platform being supported by support rollers journaled in roller piers supported by said machine base; a centering device connecting said moveable platform to said machine base; guide bearings extending downwardly from said moveable platform and engaged with said guide tracks; and said guide tracks being off-set at an angle from the normal axes of rotation of said pinch rolls to provide arcuate movement of said pinch rolls in a direction away from lateral thrust with said strip.

11. The apparatus of claim 10 wherein the position of said turntables on said base is adjustable and the offset angle of said guide tracks is adjustable by adjusting the position of said turntables.

12. The apparatus of claim 10 wherein the off-set angle is greater than zero degrees but not greater than ten degrees.

13. In apparatus for feeding a continuous strip of metal between a pair of pinch rolls, the improvement comprising a base, a pinch roll stand shiftably mounted on said base, guide means secured between said pinch roll stand and said base adapted to permit one end of said roll stand to shift transversely and rearwardly away from a condition of lateral thrust between said rolls and said strip, and the other end of said roll stand to shift transversely away from a condition of lateral thrust between said rolls and said strip.

14. In apparatus for feeding a continuous strip of metal between a pair of pinch rolls, the improvement comprising a base, a pinch roll stand shiftably mounted on said base, guide means secured between said pinch roll stand and said base adapted to permit one end of said roll stand to shift transversely and forwardly away from a condition of lateral thrust between said rolls and said strip, and the other end of said roll stand to shift transversely away from a condition of lateral thrust between said rolls and said strip.

15. Apparatus for feeding metal strip comprising a support base, a pair of opposed pinch rolls shiftable with respect to said support base, and guide means adapted to cause arcuate transverse movement of said pinch rolls toward the direction of shift of strip from the center of the rolls responsive to movement of the strip through the rolls.

16. The apparatus of claim 15, wherein said guide means comprise a pair of tracks positioned at opposite ends of said pinch rolls and whose extended longitudinal axes intersect on the entry side of the pinch rolls to provide negative angulation. 

1. Apparatus for feeding metal strip comprising a support base, a pair of vertically opposed horizontally aligned pinch rolls mounted on a horizontal platform above said support base and shiftable with respect to said support base, fixed guide means on said base with which said shiftable platform is engaged, said guide means being adapted to permit horizontal arcuate transverse movement of said platform in reaction to forces of lateral thrust between said rolls and said strip.
 2. The apparatus of claim 1 wherein said fixed guide means are a pair of tracks beneath opposite ends of said platform and offset so that straight line extensions of the longitudinal axes of the tracks intersect on the exit side of the said feed rolls.
 3. The apparatus of claim 2 wherein said tracks are adjustable within a range of off-set angles.
 4. The apparatus of claim 3 wherein said range of off-set angles is between 0* and 10*.
 5. The apparatus of claim 1 wherein said moveable platform is mounted on anti-friction means and connected to a centering device.
 6. The apparatus of claim 5 wherein said centering device includes biasing means connecting said platform to a fixed support.
 7. The apparatus of claim 1 wherein said guide means comprises a pair of members having grooves formed therein, and said moveable platform has guide bearings mounted to be received within said grooves.
 8. The apparatus of claim 1 wherein said shiftable platform is mounted on rollers carried on roller piers which are fixed relative to said moveable platform.
 9. The apparatus of claim 8 wherein said roller piers and said guide means are mounted on turnplates which are adjustable relative to the normal position of said feed rolls.
 10. Apparatus for feeding a continuous strip of metal by drawing the strip between a pair of pinch rolls comprising a support base; a pair of turnplates, one turnplate mounted at each end of said support base; a pair of guide tracks, one guide track mounted on each of said turnplates; a pair of pinch rolls mounted in a pinch roll stand, said pinch roll stand being mounted upon a moveable platform; said moveable platform being supported by support rollers journaled in roller piers supported by said machine base; a centering device connecting said moveable platform to said machine base; guide bearings extenDing downwardly from said moveable platform and engaged with said guide tracks; and said guide tracks being off-set at an angle from the normal axes of rotation of said pinch rolls to provide arcuate movement of said pinch rolls in a direction away from lateral thrust with said strip.
 11. The apparatus of claim 10 wherein the position of said turntables on said base is adjustable and the off-set angle of said guide tracks is adjustable by adjusting the position of said turntables.
 12. The apparatus of claim 10 wherein the off-set angle is greater than zero degrees but not greater than ten degrees.
 13. In apparatus for feeding a continuous strip of metal between a pair of pinch rolls, the improvement comprising a base, a pinch roll stand shiftably mounted on said base, guide means secured between said pinch roll stand and said base adapted to permit one end of said roll stand to shift transversely and rearwardly away from a condition of lateral thrust between said rolls and said strip, and the other end of said roll stand to shift transversely away from a condition of lateral thrust between said rolls and said strip.
 14. In apparatus for feeding a continuous strip of metal between a pair of pinch rolls, the improvement comprising a base, a pinch roll stand shiftably mounted on said base, guide means secured between said pinch roll stand and said base adapted to permit one end of said roll stand to shift transversely and forwardly away from a condition of lateral thrust between said rolls and said strip, and the other end of said roll stand to shift transversely away from a condition of lateral thrust between said rolls and said strip.
 15. Apparatus for feeding metal strip comprising a support base, a pair of opposed pinch rolls shiftable with respect to said support base, and guide means adapted to cause arcuate transverse movement of said pinch rolls toward the direction of shift of strip from the center of the rolls responsive to movement of the strip through the rolls.
 16. The apparatus of claim 15, wherein said guide means comprise a pair of tracks positioned at opposite ends of said pinch rolls and whose extended longitudinal axes intersect on the entry side of the pinch rolls to provide negative angulation. 